1. Field of the Invention
The present invention relates to an electrical switching apparatus operating mechanism and, more specifically to an electrical switching apparatus operating mechanism opening assembly having a cradle assembly with a pivot shaft that acts as a kicker for a toggle assembly.
2. Background Information
Electrical switching apparatus, typically, include a housing, at least one bus assembly having a pair of contacts, a trip device, and an operating mechanism. The housing assembly is structured to insulate and enclose the other components. The at least one pair of contacts include a fixed contact and a movable contact and typically include multiple pairs of fixed and movable contacts. Each contact is coupled to, and in electrical communication with, a conductive bus that is further coupled to, and in electrical communication with, a line or a load. A trip device is structured to detect an over-current condition and to actuate the operating mechanism. An operating mechanism is structured to both open the contacts, either manually or following actuation by the trip device, and close the contacts.
That is, the operating mechanism includes both a closing assembly and an opening assembly, which may have common elements, that are structured to move the movable contact between a first, open position, wherein the contacts are separated, and a second, closed position, wherein the contacts are coupled and in electrical communication. The operating mechanism includes a rotatable pole shaft that is coupled to the movable contact and structured to move each movable contact between the closed position and the open position. Elements of both the closing assembly and the opening assembly are coupled to the pole shaft so as to effect the closing and opening of the contacts.
In the prior art, an electrical switching apparatus operating mechanism closing assembly typically had a stored energy device, such as an closing spring, and at least one link coupled to the pole shaft. The at least one link, typically, included two links that acted cooperatively as a toggle assembly. When the contacts were open, the toggle assembly was in a first, collapsed configuration and, conversely, when the contacts were closed, the toggle assembly was, typically, in a second, in-line position or in a slightly over-toggle configuration. The toggle assembly typically moved through a third configuration, a reset configuration, while the contacts were open and which was a configuration during the resetting of the operating mechanism prior to closing the contacts. The opening spring biased the pole shaft to collapse the toggle assembly. The opening spring and toggle assembly were maintained in the second, in-line position by the trip device.
The force required to close the contacts was, and is, typically greater than what a human may apply and, as such, the operating mechanism typically included a mechanical closing assembly to close the contacts. The closing assembly, typically, included at least one stored energy device, such as a spring, and/or a motor. Closing springs typically were about 2 inches in diameter and about 5 to 6 inches in length. These springs were structured to apply a force of about 1000 pounds. A common configuration included a motor that compressed one or more springs in the closing assembly. That is, the closing springs were coupled to a cam roller that engaged a cam coupled to the motor. As the motor rotated the cam, the closing springs were compressed or charged.
The toggle assembly also included a cam roller, typically at the toggle joint. The closing assembly further included one or more cams disposed on a common cam shaft with the closing spring cam. Alternatively, depending upon the configuration of the cam, both the closing spring cam roller and the toggle assembly cam roller could engage the same cam. When the closing springs were released, the closing spring cam roller applied force to the associated cam and caused the cam shaft to rotate. That is, the cam roller “operatively engaged” the cam. Rotation of the cam shaft would also cause the cam associated with the toggle assembly cam roller to rotate. As the cam associated with the toggle assembly cam roller rotated, the cam caused the toggle assembly cam roller, and therefore the toggle assembly, to be moved into selected positions and/or configurations. More specifically, the toggle assembly was moved so as to rotate the pole shaft into a position wherein the contacts were closed. Thus, the stored energy from the closing springs was transferred via the cams, cam shaft, toggle assembly, and pole shaft to the contacts. Alternatively, as set forth in U.S. patent application Ser. No. 11/693,198, filed Mar. 29, 2007, which is incorporated herein by reference, a closing assembly may also utilize a ram assembly to act upon the toggle assembly. That is, as opposed to a cam moving the toggle assembly into the second, over-toggle position, a linearly traveling ram acts upon the toggle assembly at the toggle joint.
The electrical switching apparatus operating mechanism opening assembly is structured to open the contacts by allowing the pole shaft to rotate. That is, a trip device included an over-current sensor, a latch assembly and may have included one or more additional links that were coupled to the toggle assembly. Alternately, the latch assembly was directly coupled to the toggle assembly. When an over-current situation occurred, the latch assembly was released allowing the opening spring to cause the toggle assembly to collapse. When the toggle assembly collapsed, the toggle assembly link coupled to the pole shaft caused the pole shaft to rotate and thereby move the movable contacts into the open position. The latch assembly could also be actuated manually if desired.
The electrical switching apparatus operating mechanism opening assembly is responsive to the release of the latch assembly and is structured to move the toggle assembly into the first, collapsed configuration. Typically, the latch assembly included a latch plate that was structured to rotate or pivot within the housing assembly. The latch plate included a latch edge that selectively engaged a D-shaft. When the D-shaft was in a first position, the D-shaft allowed the latch plate to pivot. When the D-shaft was in a second configuration, the latch plate latch edge engaged the D-shaft and the latch plate could not rotate. The D-shaft was controlled by the trip device or by a manual input.
One or more links extended between the latch plate and the toggle assembly. When the latch plate was held in place by the D-shaft, the motion of the toggle assembly is controlled by the rotation of the pole shaft and the closing assembly. When the latch plate is free to pivot, the latch plate, via the links, caused the toggle assembly to move. Thus, when the trip device, or a manual input, caused the D-shaft to rotate, the latch plate was free to pivot which in turn caused the toggle assembly to move from the second, over-toggle configuration to the first, collapsed configuration thereby allowing the contacts to separate. To reset the operating mechanism opening assembly prior to the closing of the contacts by the closing assembly, the toggle assembly typically moved into a reset configuration. In this configuration the contacts are open, but the D-shaft is reset and the latch plate latch edge re-engages the D-shaft. Thus, the latch plate is no longer free to rotate and the motion of the toggle assembly is controlled by the pole shaft and the closing assembly as set forth above.
The operating mechanism opening assembly typically included a stop/kicker pin. The stop/kicker pin was typically disposed in one of two locations, either on the link between the latch plate and the toggle assembly or fixed to the housing assembly. The stop/kicker pin initially stops the motion of the toggle assembly during closing. That is, the stop/kicker pin, acting in the stop pin capacity, was positioned so that when the closing assembly moved the toggle assembly through the toggle, the stop/kicker pin arrested the motion of the toggle assembly in the second, over-toggle configuration. Typically, without the stop/kicker pin, the toggle assembly would collapse in a reverse direction. When the latch plate was released, the motion of the latch plate would cause the link between the latch plate and the toggle assembly to move toward the toggle assembly or, of the kicker pin was fixed, caused the toggle assembly to move toward the kicker pin. As the stop/kicker pin was contacting the toggle assembly and holding the toggle assembly in the second, over-toggle configuration, the relative motion of the stop/kicker pin toward the toggle assembly caused the toggle assembly to pass back through the in-line position and, once the toggle assembly was through the toggle, the toggle assembly could collapse. That is, the stop/kicker pin caused the toggle assembly to move into the first, collapsed configuration. Typically, there was some delay in the relative motion of the kicker pin and the toggle assembly because the stop/kicker pin was typically spaced from the pivot point of the associated link or the toggle assembly. That is, as the assembly that moved would initially move with a slow angular velocity about a pivot point that is distant from the kicker pin. Thus, the time between a release of the latch plate and the collapse of the toggle assembly was extended. This is a disadvantage as the contacts are not separated until the toggle is substantially collapsed.
In this configuration, the operating mechanism opening assembly and closing assembly are disposed adjacent to each other. The closeness of the operating mechanism opening assembly and closing assembly can create interference problems that must be addressed. For example, after the closing assembly moves the toggle assembly into the second, over-toggle configuration, the closing assembly closing device, e.g. the cam or ram as set forth above, is still disposed immediately adjacent to the toggle assembly. Under normal operating conditions, the closing assembly closing device is simply reset, thereby moving the closing assembly closing device away from the toggle assembly. If, however, an over-current condition occurs immediately after the closing of the contacts, the closing assembly closing device and the toggle assembly must be separated so that the toggle assembly may collapse. Present configurations of the operating mechanism typically cause the closing assembly closing device to be moved out of the way or allow the toggle assembly links to be separated. Both of these solutions have disadvantages. An assembly structured to move the closing assembly closing device away from the toggle assembly increases charging difficulty. An assembly structured to separate the toggle links, and subsequently recouple the toggle links adds complexity to the opening assembly.
There is, therefore, a need for an electrical switching apparatus operating mechanism opening assembly wherein the kicker pin and the associated pivot point correspond to each other.
There is a further need for an electrical switching apparatus operating mechanism opening assembly wherein the toggle assembly is moved away from the closing assembly closing device rather than having the toggle assembly separate or having the closing assembly closing device move away from the toggle assembly.